The Structure, Characterization, and Magnetic Properties of Ca4–xNixIrO6 (x = 0.25, 0.5)

✍ Scribed by John B. Claridge; Ralph C. Layland; W. Hampton Henley; Hans-Conrad zur Loye

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: German
• Weight: 114 KB
• Volume: 624
• Category: Article
• ISSN: 0372-7874
• DOI: 10.1002/(sici)1521-3749(1998120)624:12<1951::aid-zaac1951>3.0.co;2-g

✦ Synopsis

Ca 4±x Ni x IrO 6 (x = 0.25, 0.5) crystallizes with trigonal (rhombohedral) symmetry in the space group R3c, Z = 6, for Ca 3.75 Ni 0.25 IrO 6 a = 9.3013(1) A Ê , c = 11.1554(1) A Ê ; for Ca 3.5 Ni 0.5 IrO 6 a = 9.2723(1) A Ê , c = 11.0825(1) A Ê . Ca 3.75 Ni 0.25 IrO 6 and Ca 3.5 Ni 0.5 IrO 6 are isotypic to compounds of the Sr 4 PtO 6 structure type. The structure of Ca 3.75 Ni 0.25 IrO 6 has been solved by means of single crystal X-ray diffraction data analysis with the reliability factors of R = 0.019 and R w = 0.022. Also, both structures have been determined by Rietveld refinement of powder X-ray diffraction data. The structure consists of chains of alternating face-sharing IrO 6 octahedra and (Ca/Ni)O 6 trigonal prisms. The chains are separated by the calcium cations which are in a distorted square antiprismatic coordination. Magnetic measurements revealed that both Ca 3.75 Ni 0.25 IrO 6 and Ca 3.5 Ni 0.5 IrO 6 follow Curie-Weiss behavior at high temperatures. Ca 3.75 Ni 0.25 IrO 6 undergoes a single antiferromagnetic transition at T N = 5 K whereas Ca 3.5 Ni 0.5 IrO 6 undergoes two antiferromagnetic transitions at T N1 = 13 K and T N2 = 4 K.